Flashlight Fish
What is a flashlight fish? It’s a type of fish named for a pair of “glowing” organs. These are located just below each eye, which can make the fish look like a flashlight. The fact is that there are different types of fish that collectively are referred to as flashlight fish. There is also a fish called lantern fish, but this kind glows all along the body, instead of at just the head.
Flashlight fish tends to be black or dark blue in color. Most often, they reside in deep, dark oceans. When plants and animals are able to produce light through a chemical reaction, it’s called bioluminescence. This kind of luminescence produces very little heat. Estimates are that over 90% of sea creatures are capable of some kind of bioluminescence. The flashlight fish is a very particular example of this type of luminescence. Symbiotic bacteria, kept in organs beneath each eye, is the reason for the light.
These organs are used by the flashlight fish to produce this light. It actually allows the fish to control the direction of the light to a large extent. As a result, the fish can turn the light on and off, by changing the direction of the illumination. If they want to remain dark to avoid predators, they can.
The light is also used to communicate with each other, with a variety patterns of flashing used to provide different messages for warning as well as mating. These fish are the reason for stories of sailors who used the fish as guides to navigate through dangerous areas, by watchin the glowing fish beneath the water.